Frangible Airfoil with Shape Memory Alloy Inserts
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Solution Overview
Problem
Current airfoil designs in gas turbine engines face challenges with controlled and consistent failure modes, leading to increased weight and cost due to the need for trench-filler materials to mitigate load transfer and unbalance, especially under conditions like foreign object damage or extreme unbalance.
Innovation Solution
Incorporating a frangible airfoil portion with shape memory alloy (SMA) inserts that deform or partially detach from the residual airfoil portion along a defined frangible line, reducing load transfer and allowing for controlled failure, thereby reducing the necessity for extensive trench-filler materials and resulting in a lighter fan case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trench-filler material is included in the fan case to mitigate load transfer, then the fan case can withstand impact and adverse conditions, but the fan case becomes larger and heavier
Solution Approach 1:
The airfoil is divided into a frangible portion and a residual portion, allowing controlled separation during failure events. This segmentation enables the frangible portion to deform or detach, reducing load transfer to the fan case, thereby reducing the amount of trench-filler material needed and reducing fan case weight while maintaining reliability.
Solution Approach 2:
The frangible portion is extracted as a separate functional element from the main airfoil structure. By removing and controlling the failure of this specific portion, the system reduces the protective measures needed for the overall structure, decreasing fan case weight while maintaining safety.
2Strength
If traditional airfoil design is used without controlled failure mechanisms, then structural integrity is maintained, but load transfer to the fan case increases requiring more trench-filler material
Solution Approach 1:
The airfoil is segmented into frangible and residual portions, allowing controlled failure of the frangible portion during adverse events. This reduces the load transfer to the fan case, decreasing the quantity of trench-filler material required while maintaining overall structural integrity through the residual portion.
Solution Approach 2:
The potential harm of airfoil failure is converted into a beneficial controlled failure mechanism. The frangible portion is designed to fail in a predictable manner, reducing load transfer and protecting the fan case, thereby reducing the amount of protective trench-filler material needed.
3Weight of stationary object
If frangible airfoil portion is designed to deform or detach, then load transfer to fan case is reduced, but manufacturing complexity increases due to SMA insert integration
Solution Approach 1:
The airfoil combines composite materials (carbon fiber reinforced polymer) with shape memory alloy inserts to create a frangible portion with controlled failure characteristics. This composite approach enables the desired functionality while managing manufacturing complexity through integrated material selection.
Solution Approach 2:
The shape memory alloy inserts change their mechanical parameters (stiffness, strength) in response to temperature or stress changes, enabling controlled deformation or detachment of the frangible portion. This parameter change mechanism provides the desired functionality without requiring complex mechanical actuation systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The SMA inserts enable a controlled deformation of the airfoil, reducing unbalance and vibrations, and minimizing material loss during events like bird strikes, while also reducing the weight and cost of the fan case by minimizing the amount of trench-filler material required.
Implementation Method 1
a frangible airfoil portion extending between the leading edge and the trailing edge and extending along the span between the tip and the frangible line, the frangible airfoil portion including one or more shape memory alloy (SMA) inserts
Data Source
AI summary
An airfoil including a plurality of composite plies extending from a leading edge to a trailing edge and between a tip and a root. The airfoil further includes a frangible airfoil portion at the tip extending between the leading edge and the trailing edge and extending between the tip and a frangible line along a span. The frangible airfoil portion including a plurality of composite plies and one or more shape memory alloy inserts disposed between the plurality of composite plies. A gas turbine engine including a frangible airfoil and methods for forming a frangible airfoil are also disclosed.